In chemistry, hypomanganate, also called manganate(V) or tetraoxidomanganate(3−), is a trivalent anion (negative ion) composed of manganese and oxygen, with formula MnO3−4.
Hypomanganates are usually bright blue. Potassium hypomanganate K3MnO4 is the best known salt, but sodium hypomanganate Na3MnO4, barium hypomanganate Ba3(MnO4)2, and the mixed potassium-barium salt KBaMnO4 is also known. The anion can replace phosphate PO3−4 in synthetic variants of the minerals apatite and brownmillerite.